Nice little motivating article about self doubt on The Recording Revolution. In it, there's a great video with Dave Pensado where he has a huge Q&A on mixing. It's a great video for anyone interested in mixing for music.

When you sit down to mix, do it in manageable chunks. Learn when your breaking point is: that moment when the “fake” you, the doubting and fearful you, starts to show up.

It’s at this point you need to save your work and walk away. Otherwise you risk working in a danger zone of confusion and conflicting emotions. You could easily end up undoing all your good work and replacing it with worse work.